Resistance for electric circuits.



No. 743,607. PATENTED NOV. 10, 1903.

G. WRIGHT.

RESISTANCE FOR ELECTRIC CIRCUITS.

APPLICATION FILED JULY 15, 1902. RENEWED SEPT. 26, 1903.

N0 MODEL.

1 I 'F EJ I J 12 I 7 1 J l E 2 EMU-ammo 8 1: $2 4 4 M WW /E322 A,

UNITED STATES Iatented November 10, 1903.

PATENT OFFICE.

GILBERT WRIGHT, OF PITTSFIELD, MASSACHUSETTS, ASSIGNOR TO THE STANLEYELECTRIC MANUFACTURING COMPANY, OF PITTSFIELD, MASSACHUSETTS, ACORPORATION OF NEW JERSEY.

RESISTANCE FOR ELECTRIC CIRCUITS.

SPECIFICATION forming part of Letters Patent No. 743,607, dated November10, 1903.

Application filed July 15, 1902. Renewed September 26, 1903. Serial No.174,828. (No model.)

To aZZ whom it may concern:

Beitknown that I,GILBERT WRIGHT, a citizen of the United States,residingat Pittsfield, in the county of Berkshire, State of Massachusetts, haveinvented certain new and useful Improvements in Resistances for ElectricCircuits, of which the following isa full, clear, and exact description.

My invention relates to resistance for use in electric circuits.

Among the objects of myinvention are compactness, strength, anddurability of construction.

In addition to providing a resistance possessing superior structuralfeatures the arrangement of the parts is such that they all may bereadily assembled and firmly held in permanent and fixed position saveas to any part or parts intentionally made movable. Conspicuous amongthe features of improvement is the new form of the resistance unit, themethod of mechanically connecting a plurality of these units together,and the method of holding the same in place.

In the drawings,Figure 1 is an end elevation of a resistance-boxembodying'my invention the end plate being partly broken away to showfeatures of internal arrangement. Fig. 2 is a cross-sectional elevationof the parts shown in Fig. 1, but showing one grid or resistance unitonly with part of another. Fig. 3 is a perspective view of a grid orunit of resistance.

A and B represent main terminal wires of an electric circuit. Thecurrent may be considered as passing in through the wire A. The wire Aiselectrically connected, for example, by means of a binding-post C and ametallic strip C, with a brush D, which is centrally mounted and has arotary movement, said movement being given by means of a revoluble shaftD or by any other suitable means. The binding-post C may have at itsouter end contact-studs C which may stand slightly above the surface ofan end plate G, Which is preferably formed of insulating material. Theterminal B is suitably connected to the last of a series ofresistancegrids (to be hereinafter described) and may have contact-studs(not shown) similar to the contact-studs C E E are resistance units orgrids formed of suitable resistance material and formed, for example,substantially as shown in Fig. 3, so as to reduce into comparativelysmall space a resistance of considerable length, the contortions beingarranged in substantially one plane. The units E are arranged in seriesand are connected, preferably, by means of bolt-screws F, the heads ofwhich may perform the additional function of contact-studs F F. Thestuds C F are arranged inacir cle within the radius of the brush D. Eachstud F is in electrical. connection with one end of each of two adjacentgrids. The grids are arranged in series, each grid being electricallyconnected to a preceding and a succeeding grid. The grids are arrangedin radial planes from the center of the box and are mechanicallyconnected or held in such manner that there is no danger of their beingaccidentally thrown into contact with each other. In the preferred formeach grid is held at four points.

In Fig. 2 the additional reference-letter E is used to signify one endof one grid located beyond the grid E therein shown. It will be seenthat the end of the grid E (shown in Fig. 2) fits down over the shank ofthe screw F, while the adjacent end of the grid E fits onto thescrew-threaded portion of the shank F and is drawn down against the endE, so as to electrically connect the three parts F, E, and E. The otherend of the grid E (broken away in Fig. 2) may be held by another screwin the same manner as the end E. It will be seen that there is amechanical connection for each end of each grid. Intermediate in thelength of the grid E may be formed a point e, which may take into a ringH, of insulating material, held in position by means of a flange J uponthe end J of the box. This insulating material II may be of hardasbestos and may be backed with a ring of soft asbestos H. On theopposite side of the grid E a second point e is provided,- which maytake into a cavity in the rear of the plate G. As shown, each grid issecurely held in place at fourpoints. Hence there is no danger ofdislodgment and shortcircuit. When the switch is in the position shownin Fig. 1, all of the resistance units are in circuit, the currentflowing from A to the brush D, thence to the stud or studs C and thencethrough the series of radially-arranged grids to the terminal 13. To cutout the resistance, the brush D is revolved so that it will movesuccessively over the contact-studs. Inasmuch as the current alwayspasses through the brush D, it follows that when the brush is movedclockwise from the position shown in Fig. 1 one after another of theresistance units will be cut out until finally, when the brush restsupon the contact-studs connected directly with the terminal B, none ofthe units are in circuit. The reverse movement of the brush cuts in oneresistance after another. In order to prevent jumping from no resistanceto maximum resistance, a stop K may be provided located in the path ofmovement of the brush and between the terminals A B. The grids may bemade of cast-iron and in this form present a durable and economicalunit.

What I claim is 1. In a resistance for electric circuits, a pluralityof. cast grids arranged in radial planes, and retaining-lugs cast onsaid grids at points between the ends of said grids.

2. In a resistance for electric circuits, a plurality of cast gridsarranged in radial planes, retaining-lugs cast on said grids at pointsbetween the ends of said grids, and a ring of insulating materialengaging said lugs.

3. In a resistance for electric circuits, a plurality of cast gridsarranged in radial planes, an end plate of insulating material, a ringof insulating material, and lugs cast on said grids at points betweentheir ends adapted to engage said end plate and said ring.

4. In a resistance for electric circuits, a plurality of cast gridsarranged in radial planes,

retaining-lugs cast on said grids at points between their ends, and anend plate of insulating material adapted to engage said lugs.

5. In a resistance for electric circuits, a plurality of cast gridsarranged in radial planes and connected in series, an end plate ofinsulating material, a ring of insulating material, and lugs cast onsaid grids at points between their ends adapted to engage said end plateand said ring.

6. In a resistance for electric circuits, a plurality of grids cast inthe form of a strip bent back and forth on itself in parallel lines, theends of said grids being at right angles to the direction of theparallel lines and one of said ends being inclined to the plane of saidparallel lines.

7. In a resistance for electric circuits, aplurality of grids, arrangedin radial planes, said grids being cast in the form of a strip bent backand forth on itself in parallel lines, the

ends of said grids being at right angles to the direction of theparallel lines and one of said ends being inclined to the plane of theparallel lines, and means for connecting said grids in series.

8. In a rheostat, a supporting member, a plurality of rigidresistance-conductors, bolts fol-securing said resistance-conductors tosaid support, each of said bolts being arranged to secure one terminalof each of two resistanceconductors to said support, the heads of saidbolts being arranged to serve as contact-studs, and a movable switch forengaging said heads.

9. In a resistance for electric circuits, a plurality of rigidresistance-conductors arranged in radial planes, retaining-lugs on saidconductors at points between the ends of said conductors, and aplurality of clamping devices for securing the conductors to thesupporting member, each clamping device securing one end of each of twoadjacent conductors to the support, and portions of said clampingdevices serving also as contact members.

10. In a rheostat, a supporting member, a plurality of rigidresistance-conductors arranged with the ends of said conductors lying inthe arc of a circle, one end of each resistance-conductor placed betweenthe support and one end of the adjacent conductor, and a plurality ofclamping members, each of said clamping members securing one end of eachof two conductors to the support.

11. In a rheostat, a plurality of rigid counterpartresistance-conductors, each of said conductors having a reflex portionwhich lies in one plane, the reflex portions of the conductors beingarranged in radial planes and the ends of the conductors being broughtinto the arc of a circle, a support, and a plulality of bolts forclamping the conductors to the support, each of said bolts securing oneend of each of two adjacent conductors to the support, and the heads ofsaid bolts serving as contact-studs.

12. In a resistance forelcctric circuits,a plurality of rigid resistancemembers arranged in radial planes, said members being in the form of astrip bent back and forth on itself in parallel lines, the ends of saidmembers being at right angles to the direction of the parallel lines andone of said ends being inclined to the plane of the parallel lines, andbolts for connecting said members in series, the heads of said boltsserving as contact members.

Signed at Pittsfield, Massachusetts, this 9th day of July, 1902.

G1 LBE RT \V RIGHT.

Witnesses:

ARTHUR E. JENNEY, GEORGE W. HAMILTON.

